Bug#870913: general: IPv6 tunnel on host machine and container

Package: general
Severity: normal
Hi, if I setup a IPv6 tunnel over IPv4 on my machine and after setup
IPv6 tunnel on a systemd-nspawn container, I can use IPv6 on my machine
but not in container.
Host: /etc/network/interfaces: http://paste.debian.net/plain/980083
Container: /ect/network/interfaces: http://paste.debian.net/plain/980084
If in host delete line «auto ipv6», reboot, boot up container, I have
IPv6 connection on container but (obviously) not in host. If (whitout
poweroff container or ifdown ipv6) I run «ifup ipv6» on host, I have not
IPv6 connection on host. If I run «ifdown ipv6» on container, «ifdown
ipv6 && ifup ipv6» on host, I not have IPv6 connection.
-- System Information:
Debian Release: 9.1
APT prefers stable
APT policy: (500, 'stable')
Architecture: amd64 (x86_64)
Kernel: Linux 4.9.0-3-amd64 (SMP w/1 CPU core)
Locale: LANG=es_ES.utf8, LC_CTYPE=es_ES.utf8 (charmap=UTF-8), LANGUAGE=es_ES.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)